Tether for tubes of an exhaust system joint

ABSTRACT

A tether for connecting tubes includes two mutually spaced pads, each pad located on an opposite side of a lateral axis and releasably connectable to one of the tubes, an elastic stretchable connector that provides structural continuity between the pads, and handles, each handle located at an opposite axial end of the tether, suited to be gripped manually for the application of tensile force to the tether.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a joint of an exhaust system, andmore particularly to an elastic tether that holds the tubular componentsof the joint together until a clamp is secured.

2. Description of the Prior Art

A ball-and-flare joint is used to connect tubes of an engine exhaustsystem of a motor vehicle. After the tubes are fitted together, thejoint is secured by tightening the bolt of a band clamp that surroundsthe joint and provides a hoop compression force to the joint.

While connecting the tubes, the joint can easily separate due to weightof the assembly, its angular orientation in the vehicle, or incompleteassembly of the joint before securing the tubes together. If the jointis tightened while the tubes are separated, the joint will leak engineexhaust gas and produce excessive noise. Before the joint is secured bytightening a clamp, the tubes of the joint are susceptible to becomingdisengaged due to twisting forces produced at joints elsewhere in theexhaust system. The separated joint, however, may appear to be engaged,when, in fact, it is not. Detection of a separated joint is difficult.

A need exists in the industry for a tether that facilitates reliableassembly of engine exhaust system tubes in a motor vehicle, such thatthe tether holds the tubes together while an operator completes assemblyand connection of the tubes.

SUMMARY OF THE INVENTION

A tether for connecting tubes includes two mutually spaced pads, eachpad located on an opposite side of a lateral axis and releasablyconnectable to one of the tubes, an elastic stretchable connector thatprovides structural continuity between the pads, and handles, eachhandle located at an opposite axial end of the tether, suited to begripped manually for the application of tensile force to the tether.

A method for connecting first and second tubes of an engine exhaustsystem includes connecting a tether to the first tube, installing aclamp over said tube, overlapping end portions of the tubes, connectingthe tether to the second tube, securing the tubes together by tighteningthe clamp; and applying tension to the tether while disconnecting thetether from one of the tubes.

The plastic tether can be removed manually with no tools after the jointis secured. The ability of the tether to stretch readily along itslength reduces the importance of precise location of the studs on bothsides of the joint, and allows the tether to span the joint whileproviding sufficient tension to hold the joint components together untilthe joint is fully completed.

Use of the tether to assemble the joint reduces labor and time requiredto pull the joint components together during assembly of the joint andbefore the joint is completed by tightening the clamp.

The scope of applicability of the preferred embodiment will becomeapparent from the following detailed description, claims and drawings.It should be understood, that the description and specific examples,although indicating preferred embodiments of the invention, are given byway of illustration only. Various changes and modifications to thedescribed embodiments and examples will become apparent to those skilledin the art.

DESCRIPTION OF THE DRAWINGS

The invention will be more readily understood by reference to thefollowing description, taken with the accompanying drawings, in which:

FIG. 1 is an isometric view of an engine exhaust system in the vicinityof a muffler;

FIG. 2 is a schematic side view showing the ball and flare joint;

FIG. 3 is an isometric view of the tether; and

FIG. 4 is an isometric end view of the muffler showing an assembledball-and-flare joint, clamp and tether.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The portion of a engine exhaust gas system for a motor vehicle shown inFIG. 1 includes a muffler 12; an outlet tube 14, welded to the exit sideof the muffler; a exhaust tip 16, welded to tube 14; hanger rods 18,secured to the inlet end of the muffler; an inlet tube 20, welded to theinlet side of the muffler; a cylindrical clamp 22 having a partialspherical inner contour; and an elastic, stretchable tether 24,releasably secured to the inlet tube 20 and extending over the clamp 22.

The inlet tube 20 is connected by a ball-and-flare joint 26 to a tube28, located upstream of the inlet tube. FIG. 2 shows that the end ofinlet tube 20 is formed with a flare 30 having partial sphericalcontour. Tube 28 is formed with a portion 32 having a partial sphericalcontour that is received within the flare 30, and a portion 34 having apartial spherical contour, which is located adjacent flare 30 when thejoint 26 is assembled. Clamp 22 surrounds the ends of tubes 20, 28 andsecures them together when a threaded fastener 36, such as a bolt 36 orscrew on the clamp is tightened.

As FIG. 3 shows tether 24 is substantially symmetric about a lateralaxis 40. Located at each side of axis 40 is a circular pad 42 formedwith a centered hole 44; a handle 46 connected to the pads and suited tobe gripped manually by the operator who assembles joint 26; and anelastically stretchable connector 48, preferably in the form of a thinstrip or rod that provides structural continuity between the pads 42.Tether 24 is of plastic, preferably Elastollan S95A55N, which isavailable commercially from BASF. Preferably connector 48 may be a thinrod having a diameter of about 2.5 mm; the distance between holes 42 isabout 82.0 mm; the length of the tether 24 is about 144.5 mm; thethickness of the tether is about 3.5 mm; and the width of the handles 46is about 62.8 mm.

The procedure for connecting tubes 20 and 28 and producing joint 26 isdescribed with reference to FIGS. 1 and 4. Tether 24 is secured to inlettube 20 by forcing one of the holes 44 over a stud 50 that extendsoutward from the surface of tube 20. Clamp 22, which is welded at tab 52to inlet tube 20, is fitted loosely over the flare 30 of tube 20. Thenpipes 20, 28 are engaged by fitting the end portion 32 of tube 28 isfitted into the flare 30 of inlet tube 20. Tether 24 is secured to tube28 preferably by gripping the handle at the end opposite tube 20,stretching the tether longitudinally by applying tension to the tetherand forcing the other hole 44 nearest tube 28 over a stud 54 thatextends outward from the surface of tube 28. The end portion 32 of tube28 is fitted into the flare 30 of inlet tube 20. Clamp 22 is securedaround joint 26 by tightening bolt 36. The tether 24 is disconnectedfrom one of the tube 20, 28 while applying tension to the correspondinghandle 46 and disconnecting the pad 44 from its engagement with thecorresponding tube stud 50, 54. Then the tether 24 is disconnected fromthe other one of the tube 20, 28 by disconnecting the corresponding padfrom its engagement with the corresponding tube stud 50, 54.

In accordance with the provisions of the patent statutes, the preferredembodiment has been described. However, it should be noted that thealternate embodiments can be practiced otherwise than as specificallyillustrated and described.

The invention claimed is:
 1. A method for connecting first and secondtubes of an engine exhaust system, comprising: (a) connecting a tetherto the first tube; (b) installing a clamp over said tube; (c)overlapping end portions of the tubes; (d) connecting the tether to thesecond tube; (e) securing the tubes together by tightening the clamp;(f) disconnecting the tether from the tubes.
 2. The method of claim 1,wherein step (a) further comprises connecting the tether to the firsttube by forcing a hole in the tether over a projection that extends froma surface of the first tube.
 3. The method of claim 1, wherein step (b)further comprises: forming a flair in the end portion of one of thetubes; and loosely fitting the clamp over the flair.
 4. The method ofclaim 1, wherein step (c) further comprise: stretching the tetherlongitudinally by applying tension to the tether; and placing anotherhole in the tether over a projection that extends outward from a surfaceof the second tube.
 5. The method of claim 4, wherein stretching thetether longitudinally further comprises gripping a handle of the tetherat an end of the tether opposite the first tube and applying tensileforce to the handle.
 6. The method of claim 1, wherein step (c) furthercomprise: using the tether to produce an elastic force tending to holdthe tubes together while performing steps (d) and (e).
 7. The method ofclaim 1, wherein step (e) further comprises securing the tubes togetherby tightening a fastener that engages the clamp.
 8. The method of claim1, wherein step (f) further comprises while applying tension to thetether, disconnecting the tether from one of the tubes; anddisconnecting the tether from another one of the tubes.
 9. A method forconnecting first and second tubes of an engine exhaust system,comprising: (a) connecting a tether to the first tube; (b) overlappingend portions of the tubes; (c) connecting the tether to the second tube;(d) securing the tubes together; (e) disconnecting the tether from thetubes.
 10. The method of claim 9, wherein step (a) further comprisesconnecting the tether to the first tube by forcing a hole in the tetherover a projection that extends outward from a surface of the first tube.11. The method of claim 9, wherein step (b) further comprise: stretchingthe tether longitudinally by applying tension to the tether; and placinganother hole in the tether over a projection that extends from a surfaceof the second tube.
 12. The method of claim 11, wherein stretching thetether longitudinally further comprises gripping a handle of the tetherat an end of the tether opposite the first tube and applying tensileforce to the handle.
 13. The method of claim 9, wherein step (b) furthercomprise: using the tether to produce an elastic force tending to holdthe tubes together while performing steps (c) and (d).
 14. The method ofclaim 9, wherein step (d) further comprises securing the tubes togetherby tightening a fastener that engages a clamp.
 15. The method of claim9, wherein step (e) further comprises while applying tension to thetether, disconnecting the tether from one of the tubes; anddisconnecting the tether from another one of the tubes.
 16. A tether forconnecting tubes, comprising: two mutually spaced pads, each pad locatedon an opposite side of a lateral axis and releasably connectable to oneof the tubes; an elastic stretchable connector that provides structuralcontinuity between the pads; and handles, each handle located at anopposite the axial end of the tether, suited to be gripped manually forthe application of tensile force to the tether.
 17. The tether of claim16 wherein each pad is formed with a hole through a thickness of thepad, the hole being engageable with a projection extending from one ofthe tubes.
 18. The tether of claim 16 wherein the tether is formed ofplastic material and the connector is in the form of one of a strip thatconnects the pads and a rod that connects the pads.
 19. An exhaustsystem assembled by an improved method, comprising: a tether; a firsttube having a projection adapted for connection to a first end of thetether; a second tube adapted for assembly to the first tube in anoverlapping manner, the second tube having a projection adapted forconnection to a second end of the tether; a clamp for securing the firstand second tubes while the tubes are connected to the tether, whereinthe first and second tubes are restrained by the tether during assemblyuntil the clamp is secured.
 20. The exhaust system of claim 19, whereinthe tether is removed from the system after the clamp is secured.